diff --git a/AGENTS.md b/AGENTS.md
index 2e708f41fa..d16d8988db 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -11,6 +11,11 @@
 **NEVER kill Unity without asking the user first.** The user might be actively using the Unity Editor. Do not kill,
 force-quit, terminate, or otherwise stop Unity processes unless the user explicitly approves that specific action.
 
+**NEVER change Unity's default/open scene as part of running checks.** Unity batchmode or editor validation may write
+scene-selection churn such as `ProjectSettings/EditorBuildSettings.asset`, `ProjectSettings/SceneTemplateSettings.json`,
+or scene files simply because a different scene was open or loaded. Treat those as unintended local environment changes:
+do not stage them, and restore them before committing unless the user explicitly asked to change scenes/build settings.
+
 ## CRITICAL GIT RULES (NEVER VIOLATE)
 
 **NEVER use `git -C`.** Just run `git` directly from the cwd — it finds the repo via `.git` discovery. Do not `cd` to the repo root either (see the no-`cd` bash rule above).